Clock Recovery System

Transcription

1 The recovers the service clock using Adaptive Clock Recovery (ACR) and Differential Clock Recovery (DCR). Finding Feature Information, on page 1 Information About Clock Recovery, on page 1 Prerequisites for Clock Recovery, on page 2 Restrictions for Clock Recovery, on page 3 How to Configure ACR and DCR, on page 3 Associated Commands, on page 8 Additional References for Clock Recovery, on page 9 Finding Feature Information Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to An account on Cisco.com is not required. Information About Clock Recovery Adaptive Clock Recovery (ACR) Adaptive Clock Recovery (ACR) is an averaging process that negates the effect of random packet delay variation and captures the average rate of transmission of the original bit stream. ACR recovers the original clock for a synchronous data stream from the actual payload of the data stream. In other words, a synchronous clock is derived from an asynchronous packet stream. ACR is a technique where the clock from the TDM domain is mapped through the packet domain, but is most commonly used for Circuit Emulation (CEM). Effective Cisco IOS XE Everest , ACR is supported on the 8-port T1/E1 interface module. 1

2 Differential Clock Recovery (DCR) Differential Clock Recovery (DCR) Differential Clock Recovery (DCR) is another technique used for Circuit Emulation (CEM) to recover clocks based on the difference between PE clocks. TDM clock frequency are tuned to receive differential timing messages from the sending end to the receiving end. A traceable clock is used at each end, which ensures the recovered clock is not affected by packet transfer. Benefits of Clock Recovery Customer-edge devices (CEs) can have different clock from that of the Provide-edge devices (PEs). Scaling Information IM Card 48-Port T3/E3 CEM Interface Module Pseudowires Supported (Number of Clocks Derived) 1344 Prerequisites for Clock Recovery The clock of interface modules must be used as service clock. 2

3 Restrictions for Clock Recovery CEM must be configured before configuring the global clock recovery. RTP must be enabled for DCR in CEM, as the differential clock information is transferred in the RTP header. Restrictions for Clock Recovery The reference clock source is used and locked to a single clock. The clock ID should be unique for a particular interface module for ACR/DCR configuration. How to Configure ACR and DCR Configuring ACR for T3/E3 Configuring Adaptive Clock Recovery of T3/E3 Interfaces for SAToP Before You Begin The node (router) on which the 48-Port T3/E3 interface module is configured for ACR, must have its own clock derived from BITS/GPS/Stratum clock. The minimum packet size of CEM pseudowires on the network that delivers robust clock recovery is 256 bytes. To configure the clock on T3/E3 interfaces for SAToP in controller mode, use the following commands: enable configure terminal controller t3/e3 0/0/1 cem-group 0 unframed clock source recovered 1 To configure the clock recovery on T3/E3 interfaces in global configuration mode, use the following commands: clock recovered 1 adaptive cem 1 0 Note The clock configuration on controller must be done before configuring the clock recovery on global configuration mode. Verifying Adaptive Clock Recovery Configuration of T3/E3 Interfaces for SAToP Use the show recovered-clock command to verify the adaptive clock recovery of T3/E3 interfaces for SAToP: 3

4 Configuring DCR for T3/E3 Router# show recovered-clock Recovered clock status for subslot 0/ Clock Type Mode CEM Status Frequency Offset(ppb) Circuit-No 0 DS3 ADAPTIVE 0 ACQUIRED n/a 0 (Port) Use the show running-config section command to verify the configuration of adaptive clock of T3/E3 interfaces: Router# show running-config section 0/0/1 controller MediaType 0/0/1 mode t3 controller T3 0/0/1 cem-group 0 unframed clock source recovered 1 cablelength 224 interface CEM0/0/1 no ip address Use the show running-config section recovered-clock command to verify the recovery of adaptive clock of T3/E3 interfaces: Router# show running-config section recovered-clock clock recovered 1 adaptive cem 1 0 Configuring DCR for T3/E3 Configuring Differential Clock Recovery of T3/E3 Interfaces for SAToP Before You Begin Before you start configuring DCR, RTP must be enabled on the CEM interface. The RTP is used to carry the differential time. The minimum packet size of CEM pseudowires on the network that delivers robust clock recovery is 256 bytes. To configure differential clock recovery on T3/E3 interface for SAToP in controller mode, use the following commands: enable configure terminal controller t3/e3 0/0/1 cem-group 0 unframed clock source recovered 1 To configure RTP header under interface, use the following commands: interface /0/1 4

5 Verifying the Differential Clock Recovery Configuration of T3/E3 Interfaces for SAToP rtp-present To configure differential clock recovery of T3/E3 interface in global configuration mode, use the following commands: clock recovered 1 differential cem 1 0 Note The clock configuration on controller must be done before configuring the clock recovery on global configuration mode. Verifying the Differential Clock Recovery Configuration of T3/E3 Interfaces for SAToP Use the show recovered-clock command to verify the differential clock recovery of T3/E3 interfaces for SAToP: Router# show recovered-clock Recovered clock status for subslot 0/ Clock Type Mode CEM Status Frequency Offset(ppb) Circuit-No 0 DS3 DIFFERENTIAL 0 ACQUIRED n/a 0 (Port) Use the show running-config section command to verify the configuration of differential clock of T3/E3 interfaces for SAToP: Router# show running-config section 0/0/1 controller MediaType 0/0/1 mode t3 controller T3 0/0/1 cem-group 0 unframed clock source recovered 1 cablelength 224 interface CEM0/0/1 no ip address rtp-present Use the show running-config section recovered-clock command to verify the recovery of differential clock of T3/E3 interfaces: Router# show running-config section recovered-clock clock recovered 1 differential cem 1 0 5

6 Configuring ACR for Channelized T3/T1 or E3/E1 Configuring ACR for Channelized T3/T1 or E3/E1 Configuring Adaptive Clock Recovery of Channelized T3/T1 or E3/E1 Interfaces for SAToP Before You Begin The node (chassis) on which the T3/T1 or E3/E1 is configured for ACR, has to have its own clock derived from BITS/GPS/Stratum clock. The minimum packet size of CEM pseudowires on the network that delivers robust clock recovery is 256 bytes. To configure adaptive clock on a channelized T3/T1 or E3/E1 interfaces under controller for SAToP in controller mode, use the following commands: enable configure terminal controller t3/e3 0/0/1 t1/e1 1 cem-group 0 unframed t1/e1 1 clock source recovered 1 To configure recovery of adaptive clock of channelized T3/T1 or E3/E1 interfaces in global configuration mode, use the following commands: clock recovered 1 adaptive cem 1 0 Note The clock configuration on controller must be done before configuring the clock recovery on global configuration mode. To remove the clock configuration in ACR and DCR, you must remove the recovery clock configuration in global configuration mode and then remove the controller configuration. Verifying the Adaptive Clock Recovery Configuration of Channelized T3/T1 or E3/E1 Interfaces for SAToP Use the show recovered-clock command to verify the adaptive clock recovery of T3/T1 or E3/E1 interfaces for SAToP: Router# show recovered-clock Recovered clock status for subslot 0/ Clock Type Mode CEM Status Frequency Offset(ppb) Circuit-No 0 DS3-ds1 ADAPTIVE 0 ACQUIRED n/a 0/1 (Port/t1) Use the show running-config section command to verify the configuration of adaptive clock of channelized T3/T1 or E3/E1 interfaces: Router# show running-config section 0/0/1 controller MediaType 0/0/1 6

7 Configuring DCR for Channelized T3/T1 or E3/E1 mode t3 controller T3 0/0/1 framing c-bit cablelength 224 t1 1 cem-group 0 unframed t1 1 clock source recovered 1 interface CEM0/0/1 no ip address Use the show running-config section recovered-clock command to verify the recovery of adaptive clock of channelized T3/T1 or E3/E1 interfaces: Router# show running-config section recovered-clock clock recovered 1 adaptive cem 1 0 Configuring DCR for Channelized T3/T1 or E3/E1 Configuring Differential Clock Recovery of Channelized T3/T1 or E3/E1 Interfaces for SAToP Before You Begin Before you start configuring DCR, RTP must be enabled on the CEM interface. The RTP is used to carry the differential time. The minimum packet size of CEM pseudowires on the network that delivers robust clock recovery is 256 bytes. To configure differential clock on a channelized T3/T1 or E3/E1 interfaces under controller in controller mode, use the following commands: enable configure terminal controller t3/e3 0/0/1 t1/e1 1 cem-group 0 unframed t1/e1 1 clock source recovered 1 To configure RTP header under channelized T3/T1 or E3/E1 interfaces, use the following commands: interface /0/1 rtp-present To configure recovery of differential clock of channelized T3/T1 or E3/E1 interfaces in global configuration mode, use the following commands: clock recovered 1 differential cem 1 0 7

8 Verifying the Differential Clock Recovery Configuration of Channelized T3/T1 or E3/E1 Interfaces for SAToP Note The clock configuration on controller must be done before configuring the clock recovery on global configuration mode. Verifying the Differential Clock Recovery Configuration of Channelized T3/T1 or E3/E1 Interfaces for SAToP Use the show recovered-clock command to verify the differential clock recovery of T3/T1 or E3/E1 interfaces for SAToP: Router# show recovered-clock Recovered clock status for subslot 0/ Clock Type Mode CEM Status Frequency Offset(ppb) Circuit-No 0 DS3-ds1 DIFFERENTIAL 0 ACQUIRED n/a 0/1 (Port/t1) Use the show running-config section command to verify the configuration of differential clock of channelized T3/T1 or E3/E1 interfaces: Router# show running-config section 0/0/1 controller MediaType 0/0/1 mode t3 controller T3 0/0/1 framing c-bit cablelength 224 t1 1 cem-group 0 unframed t1 1 clock source recovered 1 interface CEM0/0/1 no ip address rtp-present Use the show running-config section recovered-clock command to verify the recovery of differential clock of channelized T3/T1 or E3/E1 interfaces: Router# show running-config section recovered-clock clock recovered 1 differential cem 1 0 Associated Commands The commands used to adaptive clock recovery and differential clock recovery on 48-Ports T3/E3 Interface Module. Commands clock recovered adaptive cem URL interface/command/ir-cr-book/ ir-c2.html#wp

9 Additional References for Clock Recovery Commands cem-group recovered-clock controller t3/e3 clock-source URL interface/command/ir-cr-book/ ir-c1.html#wp interface/command/ir-cr-book/ ir-o1.html#wp interface/command/ir-cr-book/ ir-c2.html#wp interface/command/ir-cr-book/ ir-c2.html#wp Additional References for Clock Recovery Related Documents Related Topic Cisco IOS commands Document Title Cisco IOS Master Commands List, All Releases Standards and RFCs Standard/RFC ITU -T G.8261 Title Timing and synchronization aspects in packet networks MIBs MIB MIBs Link To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: 9

10 Additional References for Clock Recovery Technical Assistance Description The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. Link 10